The second motherboard part of Gigabyte's G1-Killer series apart from the recently detailed G1.Guerrilla is the G1.Assassin. Also an LGA1366 motherboard based on the Intel X58 + ICH10R chipset, the G1.Assassin ropes overclockers into the equation. While the Guerrilla has more in for gamers (and support for up to 3 graphics cards in multi-GPU), the Assassin boasts of a strong CPU VRM, an arsenal of overclocker-friendly features, support for up to four graphics cards in 4-way SLI/CrossFireX, while retaining the gamer-appeal. Unlike Guerrilla, Assassin is an XL-ATX motherboard, retaining the same green+black color scheme.

It features the same 16-phase CPU VRM configuration found on the X58A-UD7 (rev 2.0). The four PCI-Express x16 slots are connected directly to the X58 northbridge, apart from one PCI-E x1 and a PCI. USB 3.0 and SATA 6 Gb/s are standard features here, too. Like the Guerrilla, it features Bigfoot Killer 2100 hardware NIC. The audio, however, is different. While Guerrilla merely uses an HD audio CODEC backed by X-Fi MB software, Assassin uses an actual CA20K2 processor that can perform hardware mixing over OpenAL in Windows 7 and Vista. The audio processor has its own 64 MB of memory, and the Killer NIC reportedly having 1 GB of DDR2 dedicated memory. A rich array of electrolytic capacitors gives the audio a more natural tone. The Assassin is also expected to have overclocking capabilities on par with the X58A-UD7/UD9 leviathans.